JP7586404B2 - How to get iodine - Google Patents

Description

The present invention relates to a method for extracting iodine from brine.

Iodine is a common element that is also found in seawater, but its presence as a resource on Earth is uneven, and it is known to exist in high concentrations only in brines (salt waters) produced in association with natural gas and petroleum, and in saltpeter ore in Chile.

Apart from the method of separating iodine from saltpeter ore, iodine is mainly produced industrially by separating it from the brine that is pumped up from permeable underground layers of rock along with dissolved natural gas, and contains iodide ions remaining after natural gas has been separated.

As methods for producing molecular iodine (I ₂ ; hereinafter, sometimes simply referred to as iodine) using brine as a raw material, the blowing out method and the ion exchange resin method are industrially practiced (see Non-Patent Document 1).

Kaiho Tatsuo "The Book of Iodine" Nikkan Kogyo Shimbun, published June 25, 2015, pp. 16-23

In the industrial extraction of iodine from natural underground brine (hereinafter simply referred to as "brine") that contains iodine atoms, it is necessary to efficiently extract the iodine components contained in the brine without loss. In particular, from the perspective of resource conservation, there is a demand for further improvement in the yield of iodine, which is a natural resource.

In addition, in the past, when obtaining iodine, there was a problem that other components contained in the brine became insoluble and precipitated, contaminating the equipment.

The present invention has been made to solve the above problems, and can be realized by the following invention.

(1) A method for extracting iodine from brine, comprising the steps of:
a pretreatment step of contacting the brine with manganese oxide activated by contacting the brine with a chlorine-based activation treatment agent ;
and an iodine obtaining step of obtaining iodine using the pretreated brine obtained through the pretreatment step.

(2) The method for obtaining iodine described in (1) above, wherein the manganese oxide to be subjected to the pretreatment step is one which has been contacted with the chlorine-based activation treatment agent and then washed with water not containing the chlorine-based activation treatment agent to remove the chlorine-based activation treatment agent remaining on the solid surface .

( 3 ) The method for obtaining iodine according to (1) or (2) above, wherein the total organic carbon (TOC) in the brackish water subjected to the pretreatment step is 10 mg/L or more.

( 4 ) The method for obtaining iodine according to any one of (1) to ( 3 ) above, wherein the iodine obtaining step is a step of obtaining iodine by a blowing out method.

The present invention provides a method for obtaining iodine that can achieve a particularly high yield of iodine from brine while preventing contamination of the iodine obtaining device.

FIG. 1 is a diagram showing an example of a preferred embodiment of the method for obtaining iodine of the present invention.

Preferred embodiments of the present invention will now be described in detail.
FIG. 1 is a diagram showing an example of a preferred embodiment of the method for obtaining iodine of the present invention.

The iodine extraction method of the present invention is a method for extracting iodine from brine, and includes a pretreatment step of contacting the brine with manganese oxide, and an iodine extraction step of extracting iodine using the pretreated brine obtained through the pretreatment step.

This makes it possible to provide a method for obtaining iodine that can achieve a particularly excellent yield of iodine from brine while preventing contamination of the iodine obtaining device.

In contrast, for example, if the pretreatment process of contacting the brine with manganese oxide is omitted and an oxidizing agent such as sodium hypochlorite is directly added to the brine to be used in the iodine extraction process, the iodine yield from the brine decreases. Furthermore, other components in the brine become insoluble and precipitate, contaminating the iodine extraction device.

[1] Brine The brine used in the present invention is natural salt water containing iodide ions (I ^- ). Economically preferable is the brine remaining after pumping from an underground brine aquifer and separating and extracting the dissolved natural gas using a natural gas separation device. Furthermore, in the present invention, underground brines with variations in iodide ion concentration, oxidized matter concentration, and pH value, such as mixed brines collected from multiple wells at any time, can also be used.

The amount of iodide ions contained in the brine is not particularly limited, but is preferably 20 mg/L or more, more preferably 30 mg/L or more, and even more preferably 40 mg/L or more.

In the present invention, the mere mention of "iodine" means molecular iodine, which has the chemical formula _I2 .

Brine pumped from underground generally contains natural water-soluble polymers. Examples of water-soluble polymers include polysaccharides with hydroxyl or carboxyl groups, humic substances such as humic acid and fulvic acid, and proteins.

The molecular weight of the water-soluble polymer contained in the brine is, for example, in the range of 500 to 2,000,000.

[2] Water Treatment Before the various steps described below, the underground brine may be subjected to water treatment to remove impurities such as sand and suspended solids from the brine. Examples of water treatment include filtration and aeration.

By carrying out such water treatment, for example, it is possible to efficiently remove insoluble matter contained in the brine and substances that cause insoluble matter that may be generated during the iodine extraction process, thereby improving the processing efficiency in the pretreatment process described in detail later, and further improving the iodine extraction rate and shortening the time required for the iodine extraction method, thereby further improving iodine productivity.

In particular, filtration can more effectively prevent contamination and blockages in the equipment and piping used in the iodine extraction process.

It is also preferable to aerate the brine with air or oxygen, for example, to precipitate the iron ions contained in the brine as iron hydroxides, and then filter out such precipitates (insoluble matter) using a filter material.

This makes it possible to more effectively prevent contamination and blockages in the equipment and piping used in the iodine acquisition process.

Filtration can be carried out, for example, by subjecting brine pumped from underground to filtration processes such as coagulation precipitation filtration, sand filtration, and porous membrane filtration, either alone or in combination.

The pore size of the porous filtration membrane is not particularly limited, but in order to balance the removal performance and the amount of permeated water, it is preferable that the average pore size is 0.01 μm or more and 1 μm or less.

Examples of filtration materials that can be used include sand, coal, activated carbon, particles of inorganic oxides or resins, and porous filtration membranes such as microfiltration membranes or ultrafiltration membranes.

For this type of water treatment, an insoluble matter removal device equipped with either a filtration treatment device or an aeration treatment device, or both, is preferably used.

[3] Pretreatment Step In the pretreatment step, the brine is brought into contact with manganese oxides.

It is believed that the pretreatment process causes the heavy metals contained in the brine to precipitate and be removed from the liquid phase, and also modifies the water-soluble polymers, reducing their reactivity with iodine.

Hereinafter, the brine after contact with manganese oxides, i.e., the brine that has been treated in the pretreatment process, will be referred to as "pretreated brine."

The brine used in the pretreatment process contains heavy metals even after water treatment, with the total iron content usually being 0.10 mg/L or more and the total manganese content usually being 0.05 mg/L or more.

In addition, even if the brine subjected to the pretreatment process has undergone water treatment, it still contains water-soluble polymers, and the total organic carbon concentration (TOC), which is an indicator of water-soluble polymers, is usually 10 mg/L or more, and more specifically, for example, 20 mg/L or more and 200 mg/L or less.

As described above, when using brine with a relatively high heavy metal content and total organic carbon concentration, there was a problem in the past that the iodine acquisition device was particularly susceptible to contamination and the yield of iodine from the brine was easily reduced. However, according to the present invention, it is possible to achieve a particularly excellent yield of iodine from the brine while fully preventing contamination of the iodine acquisition device. In other words, the effects of the present invention are more pronounced when using brine with a relatively high heavy metal content and total organic carbon concentration as described above.

In the pretreatment process, manganese oxides oxidize heavy metal ions, such as iron ions and manganese ions, contained in the brine, producing metal oxides and metal hydroxides. These can be adsorbed and removed as insoluble matter.

The manganese oxide used in the pretreatment step may be, for example, solid manganese oxide represented by MnO _x (x is a number between 1 and 2), more specifically, manganese oxide having an α-type, β-type, ε-type, γ-type, λ-type, δ-type or R-type crystal structure, or a combination of two or more selected from these. More specifically, for example, a composite of β-type manganese dioxide and γ-type manganese dioxide may be used.

Manganese ores containing manganese oxide can also be used.
Additionally, complexes of manganese oxide containing metals other than manganese may also be used.

In addition, a support in which manganese oxide is supported on a carrier (e.g., a powder, granular, honeycomb-shaped support, etc.) can be used.

For example, anthracite, zeolite, and other ceramics can be used as the carrier. Manganese oxide or a molded product of manganese oxide carrier can also be used.

When using powdered manganese oxide, the particle size of the manganese oxide is not particularly limited, but is preferably 0.2 mm or more and 5.0 mm or less, and more preferably 0.3 mm or more and 3.0 mm or less.

Furthermore, when powdered manganese oxide is used, the bulk density of the manganese oxide is not particularly limited, but is preferably 1.0 g/cm ³ or more, and more preferably 1.4 g/cm ³ or more.

Moreover, the manganese oxide may be a porous material.
This makes it possible to increase the surface area per unit volume of the manganese oxide, and the above-mentioned effects are more pronounced.

It is preferable that the manganese oxide is activated by contacting it with an activating agent.

This makes it possible to further enhance the oxidation activity against the heavy metal ions and water-soluble polymers contained in the brine.

Activation treatment agents used in the activation treatment of manganese oxides include, for example, chlorine, hypochlorite, chlorine dioxide, hydrogen peroxide, persulfate, ozone, etc., and from the standpoint of cost and oxidation activity, chlorine-based activation treatment agents such as sodium hypochlorite and chlorine are preferred, with sodium hypochlorite being particularly preferred.

The activation treatment agent may be mixed into the irrigation water before it is subjected to pretreatment. In this case, the activation treatment process can be reduced or the frequency of activation can be decreased.

This makes the above-mentioned effects more pronounced. Furthermore, even if the activity of the manganese oxide used in the iodine extraction method of the present invention decreases, it can be suitably reactivated and reused.

The temperature at which the manganese oxide is brought into contact with the activation treatment agent is not particularly limited, but is preferably 5°C or higher and 40°C or lower.

The time for which the manganese oxide is in contact with the activation treatment agent is not particularly limited, but is preferably 10 hours or less, and more preferably 0.1 to 3.5 hours.

After contacting the manganese oxide with the activating agent, it is preferable to wash the manganese oxide with water that does not contain the activating agent to remove any activating agent remaining on the solid surface.

The pretreatment process can be carried out, for example, by passing brine through a pretreatment tank filled with manganese oxide.

The flow rate of the brine to the pretreatment tank is not particularly limited, but is preferably 1 Hr ^-1 or more and 200 Hr ^-1 or less, and more preferably 5 Hr ^-1 or more and 100 Hr ^-1 or less, in terms of space velocity.

The pH of the brine to be subjected to the pretreatment step (for example, the brine to be passed through the pretreatment tank) is not particularly limited, but is preferably 10 or less, more preferably 9 or less, and even more preferably 8 or less.
In addition, in order to adjust the pH of the brine, a pH adjuster such as hydrochloric acid or sulfuric acid may be added.

The temperature of the irrigation water in the pretreatment process (e.g., the temperature of the irrigation water in the pretreatment tank) is not particularly limited, but is preferably from 0°C to 60°C.

A plurality of pretreatment tanks may be arranged in series along the flow of irrigation water.
This makes it easier to manage the pretreatment tank. A filtration device for filtering insoluble matters such as metal oxides and metal hydroxides may be provided downstream of the pretreatment tank.

In the pretreatment process, manganese oxide can be used continuously while passing the brine. The activity of manganese oxide gradually decreases as the water passes through for a long period of time, but at that point, it can be reactivated and reused by carrying out an activation treatment in which the manganese oxide is brought into contact with an activating agent.

A preferred embodiment of the present invention is a method in which multiple pretreatment tanks filled with manganese oxide are arranged in parallel, and the flow of brine is switched sequentially to the pretreatment tanks filled with active manganese oxide. In other words, the flow of brine to the pretreatment tank in which the activity of the manganese oxide has decreased is stopped, and pretreatment is carried out using the other pretreatment tanks. During this time, the pretreatment tank in which the activity has decreased is subjected to an activation treatment in which an activating agent is supplied, and the manganese oxide is reactivated in preparation for the flow of brine in the next switchover.

The pretreatment step reduces the concentrations of heavy metals contained in the brine. The heavy metal contents in the pretreated brine obtained by the pretreatment step are preferably less than 0.10 mg/L for total iron and less than 0.05 mg/L for total manganese.
This makes it possible to more effectively prevent contamination of the iodine obtaining device.

As described above, the total iron content in the pretreated brackish water obtained in the pretreatment step is preferably less than 0.10 mg/L, and more preferably less than 0.05 mg/L.
This makes the above-mentioned effects more pronounced.

As described above, the total manganese content in the pretreated brackish water obtained by the pretreatment step is preferably less than 0.05 mg/L, and more preferably less than 0.01 mg/L.
This makes the above-mentioned effects more pronounced.

The pretreatment process does not necessarily oxidize the water-soluble polymers contained in the brine to the point where they are completely decomposed.

It is believed that in the pretreatment process, manganese oxides denature the water-soluble polymer, changing its structure and physical properties, and reducing the chemical or physical bonding strength between the water-soluble polymer and iodine.

[4] Iodine Acquisition Step The pretreated brine that has been subjected to the pretreatment step is subjected to an iodine acquisition step, in which iodine is separated and acquired from the pretreated brine.

More specifically, in the iodine obtaining process, the iodide ions contained in the brine are converted to molecular iodine ( _I2 ) by an oxidation reaction caused by an oxidizing agent such as chlorine or sodium hypochlorite. Hereinafter, the brine containing molecular iodine as a result of the iodide ions being oxidized by the oxidizing agent is referred to as "oxidized brine."

In the present invention, the pretreated brine obtained through the pretreatment process has a reduced heavy metal content and reduced reactivity of the water-soluble polymer with iodine, so that undesirable side reactions of iodide ions (e.g., reactions with organic matter) can be effectively prevented from occurring in the iodine acquisition process, resulting in an excellent iodine yield.

In the iodine acquisition process, iodine can be obtained from iodide ions contained in the pretreated brine using iodine acquisition methods such as the blowing out method and the ion exchange resin method. The device that performs the iodine acquisition process is called the iodine acquisition device.

The present invention significantly improves the iodine yield in iodine acquisition devices using the blowing out method and the ion exchange resin method.

In particular, by performing the iodine acquisition process using the blowing out method, iodine can be obtained by treating large amounts of water economically compared to the ion exchange resin method. Also, compared to the case where the blowing out method is performed without carrying out a pretreatment process, it is possible to prevent contamination of the iodine diffusion tower, which is the iodine acquisition device, while achieving a particularly excellent iodine yield from the brine.

In addition, by performing the iodine acquisition process using the ion exchange resin method, iodine can be economically acquired by treating a small amount of water compared to the blowing-out method. Also, compared to the case where the ion exchange resin method is performed without carrying out a pretreatment process, it is possible to prevent contamination of the iodine adsorption tower, which is the iodine acquisition device, while achieving a particularly excellent iodine yield from the brine.

The blowing-out method involves adding an oxidizing agent to the pretreated brine, then blowing in air to volatilize the molecular iodine that is produced, which is then absorbed into an absorption solution containing a reducing agent, and an oxidizing agent is added to the absorption solution to reoxidize it and obtain iodine.

The iodine extraction process using the blowing-out method specifically includes an oxidation step in which a chlorine-based oxidizing agent such as chlorine or sodium hypochlorite is mixed with the pretreated brine to produce oxidized brine containing iodine, a stripping step in which the oxidized brine after the oxidation step is sent to a stripping tower equipped with a blower and gas such as air is blown in to vaporize the iodine, an absorption step in which the iodine-containing gas released from the stripping tower in the stripping step is brought into contact with an aqueous solution containing a reducing agent such as sulfurous acid or sodium (bis)sulfite in an absorption tower to obtain an absorption liquid containing a high concentration of iodide ions, and a crystallization step in which an oxidizing agent such as chlorine or sodium hypochlorite is added to the obtained absorption liquid to produce and obtain solid iodine.

The oxidation step by mixing an oxidizing agent in the blowing out method is preferably carried out under conditions in which the pH of the oxidizing brine to which the oxidizing agent has been added is in the acidic or neutral range. More specifically, the pH of the oxidizing brine in the oxidation step is preferably 10 or less, more preferably 9 or less, and even more preferably 8 or less.

In the ion exchange resin method, an oxidizing agent is added to the pretreated brine, and then polyiodine ions are generated via the molecular iodine that is generated. The oxidized brine containing polyiodine ions is brought into contact with an ion exchange resin, the adsorbed polyiodine ions are eluted, and an oxidizing agent is added to the eluate to reoxidize it and obtain iodine.

Specifically, the process for obtaining iodine using the ion exchange resin method includes an oxidation step in which a chlorine-based oxidizing agent such as chlorine or sodium hypochlorite is mixed with the pretreated brine to produce polyiodine ions such as I ₃ ^- ; an adsorption step in which the polyiodine ion-containing brine after the oxidation step is sent to an adsorption tower filled with an anion exchange resin to adsorb the polyiodine ions onto the anion exchange resin; an elution step in which the anion exchange resin is sent to an elution tower to elute the adsorbed polyiodine ions by contacting them with an eluent such as sulfurous acid or sodium (bis)sulfite; and a crystallization step in which an oxidizing agent such as chlorine or sodium hypochlorite is added to the eluate to produce and obtain solid iodine.

The oxidation step using an oxidizing agent in the ion exchange resin method is preferably carried out under conditions in which the pH of the oxidizing brine to which the oxidizing agent has been added is in the acidic or neutral range. More specifically, the pH of the oxidizing brine in the oxidation step is preferably 10 or less, more preferably 9 or less, and even more preferably 8 or less.

In addition, in the iodine acquisition process, iodine that forms an organic compound by chemically or physically bonding with the water-soluble polymer contained in the brine (hereinafter referred to as organic iodine) is generated. According to the inventor's investigation, organic iodine in the oxidized brine is difficult to vaporize in the stripping step of the blowing out method, and difficult to adsorb to the anion exchange resin in the adsorption step of the ion exchange resin method, and is discharged without being used. Therefore, the generation of organic iodine in the iodine acquisition process reduces the iodine yield.

On the other hand, in the present invention, the production of organic iodine is suppressed. The cause of this is presumably that the pretreatment process of the brine causes the molecular chains or functional groups of the water-soluble polymers in the brine to be oxidized by manganese oxides, causing at least some of the water-soluble polymers to change their primary or higher-order structure or become smaller in molecular weight, making them inactive and no longer able to form stable chemical or physical bonds with iodine. It is presumed that the water-soluble polymers are denatured by the pretreatment process, but the color of the brine may not be removed.

In short, compared to brine that has not been subjected to a pretreatment process, the treated brine that has been subjected to the pretreatment process of the present invention has a reduced organic iodine concentration and a significantly increased molecular iodine concentration in the iodine acquisition process. As a result, the yield of iodine from the iodide ions contained in the brine is improved in the iodine acquisition process.

It is known that natural brine pumped from underground contains heavy metals and water-soluble polymers, but it was not known that this is related to the acquisition of iodine, and furthermore, it was not known that the yield of iodine in the iodine acquisition process can be improved by contacting the brine with manganese oxides.

The above describes preferred embodiments of the present invention, but the present invention is not limited to these. For example, modifications such as changing conditions or adding other steps may be made within the scope of the spirit of the present invention.

The present invention will be described in detail below with reference to examples, but the present invention is not limited to these.

[5] Implementation of iodine acquisition method (Example 1)
First, a pretreatment tank was prepared by filling a glass chromatography tube (with a glass filter) with an inner diameter of 30 mm with 100 mL of manganese oxide A (ceramic particles (manganese oxide (MnO _x ; x is a number between 1 and 2) (manufactured by Tochemi Corporation, product name Radical Light UC3)) carrying manganese oxide as a manganese oxide. This was back-washed with ion-exchanged water, and then activation treatment was carried out by passing 3 L of water mixed with 6.76 g of a 12 mass % aqueous sodium hypochlorite solution through it at a space velocity of 10 Hr ^-1 . This was further back-washed with ion-exchanged water, and a pretreatment tank filled with activated manganese oxide was prepared.

Next, a pretreatment step was carried out by continuously passing the brine A (iodide ion content 35 mg/L, TOC content 40 mg/L, total iron content 0.15 mg/L, total manganese content 0.10 mg/L) which had been subjected to an aeration treatment by aeration with air and filtration treatment by anthracite through the pretreatment tank prepared as described above at a space velocity ^of 60 Hr and at 25 to 30°C.

The pretreated irrigation water coming out of the outlet of the pretreatment tank was collected and sampled for 60 minutes between 60 and 120 minutes after the start of irrigation.

Using the collected pretreated brine, a 12% by mass aqueous solution of sodium hypochlorite was added, and an oxidation reaction was carried out to generate molecular iodine, and an iodine extraction process was carried out using the blowing-out method, obtaining iodine. The results are shown in Table 1. The TOC of the brine discharged after the iodine extraction process was 40 mg/L, the total iron content was 0.05 mg/L, and the total manganese content was 0.01 mg/L.

Example 2
Iodine was obtained by carrying out the iodine obtaining method in the same manner as in Example 1, except that the manganese oxide used in the pretreatment step was changed to manganese oxide B (ceramic particles carrying manganese oxide (MnO _x ; x is a number between 1 and 2) (manufactured by Nihon Genryo Co., Ltd., product name New Color Cutter Light). The results are shown in Table 1.

Example 3
Iodine was obtained by carrying out the same method as in Example 1, except that the brine before the pretreatment step was aerated with air and filtered with anthracite, and then sulfuric acid was added as an additive to adjust the pH to 6.0. The results are shown in Table 1.

Example 4
Iodine was obtained by carrying out the iodine obtaining method in the same manner as in Example 1, except that brine B (iodide ion content 38 mg/L, TOC 50 mg/L, total iron content 0.35 mg/L, total manganese content 0.25 mg/L) was used as the brine passed through the pretreatment step. The results are shown in Table 2. The brine discharged after the iodine obtaining step had a TOC of 50 mg/L, a total iron content of 0.10 mg/L, and a total manganese content of 0.01 mg/L.

(Comparative Example 1)
Iodine was obtained by carrying out the iodine obtaining method in the same manner as in Example 1, except that the pretreatment step was omitted.

That is, using the brine A that had been subjected to an aeration process using air and a filtration process using anthracite, a 12% by mass aqueous solution of sodium hypochlorite was added, and an oxidation reaction was carried out to generate molecular iodine, and an iodine extraction process was carried out using the blowing-out method, thereby obtaining iodine. The results are shown in Table 1. The TOC of the brine discharged after the iodine extraction process was 40 mg/L, the total iron content was 0.15 mg/L, and the total manganese content was 0.10 mg/L.

(Comparative Example 2)
Iodine was obtained by carrying out the iodine obtaining method in the same manner as in Example 1, except that anthracite (manufactured by Tohkemi Co., Ltd., product name Anthracite 0.6 mm) was used instead of manganese oxide in the pretreatment step. The results are shown in Table 1.

(Comparative Example 3)
Iodine was obtained by carrying out the iodine obtaining method in the same manner as in Example 4, except that the pretreatment step was omitted.

That is, using brine B that had been subjected to an aeration process using air and filtration using anthracite, a 12% by mass aqueous solution of sodium hypochlorite was added, and an oxidation reaction was carried out to generate molecular iodine, and an iodine extraction process was carried out using the blowing-out method, thereby obtaining iodine. The results are shown in Table 2. The TOC of the brine discharged after the iodine extraction process was 50 mg/L, the total iron content was 0.35 mg/L, and the total manganese content was 0.25 mg/L.

For each of the above examples and comparative examples, the processing conditions for the iodine extraction method when brine A is used are summarized in Table 1, and the processing conditions for the iodine extraction method when brine B is used are summarized in Table 2.

Tables 1 and 2 show the molecular iodine (I ₂ ) concentration, organic iodine concentration, and total iodine concentration of the brine (oxidized brine) collected in the oxidation step.

Tables 1 and 2 show the organic iodine concentration and total iodine concentration of the brine collected during the iodine extraction process (brine after iodine extraction).

In addition, for each of the above examples and comparative examples, the ratio of iodine ( _I2 ) finally obtained by carrying out the iodine acquisition method to the iodide ions contained in brine A or brine B (iodine yield), and the presence or absence of visual contamination of the iodine acquisition device after carrying out the iodine acquisition method are summarized in Tables 1 and 2.

As is clear from Tables 1 and 2, excellent results were obtained in each of the above examples, whereas satisfactory results were not obtained in each of the comparative examples.

By implementing the present invention, the production of organic iodine is suppressed and the molecular iodine concentration is significantly increased in the iodine extraction process. As a result, the yield of iodine from iodide ions contained in the brine is improved in the iodine extraction process.

The iodine extraction method of the present invention is a method for extracting iodine from brine, and includes a pretreatment step of contacting the brine with manganese oxide, and an iodine extraction step of extracting iodine using the pretreated brine obtained through the pretreatment step.

According to the method for obtaining iodine of the present invention, it is possible to provide a method for obtaining iodine that can prevent contamination of an iodine obtaining apparatus while achieving a particularly excellent yield of iodine from brine.
Therefore, the method for obtaining iodine of the present invention has industrial applicability.

Claims (4)

A method for obtaining iodine from brine, comprising the steps of:
a pretreatment step of contacting the brine with manganese oxide activated by contacting the brine with a chlorine-based activation treatment agent ;
and an iodine obtaining step of obtaining iodine using the pretreated brine obtained through the pretreatment step. 2. The method for obtaining iodine according to claim 1, wherein the manganese oxide to be subjected to the pretreatment step is one from which the chlorine-based activation treatment agent has been contacted and then washed with water not containing the chlorine-based activation treatment agent to remove the chlorine-based activation treatment agent remaining on the solid surface . 3. The method for obtaining iodine according to claim 1, wherein the total organic carbon (TOC) in the brackish water subjected to the pretreatment step is 10 mg/L or more. The method for obtaining iodine according to claim 1 , wherein the iodine obtaining step is a step of obtaining iodine by a blowing out method.